Answers

I almost have the same question, I just want to use a float value, but creating constant buffer failed with E_INVALIDARG. At last, I use XMFLOAT4(the same as float4) and it's OK, actually I only use the XMFLOAT4.x to pass my parameter.
You can have a try.

I almost have the same question, I just want to use a float value, but creating constant buffer failed with E_INVALIDARG. At last, I use XMFLOAT4(the same as float4) and it's OK, actually I only use the XMFLOAT4.x to pass my parameter.
You can have a try.